This application relates to a refrigerant system utilizing tandem compressors sharing a common evaporator, but having separate condensers and wherein a reheat coil is incorporated into the system design.
Refrigerant systems are utilized in applications to change the temperature and humidity or otherwise condition the environment. In a standard refrigerant system, a compressor delivers a compressed refrigerant to a heat exchanger, known as a condenser, which is typically located outside. From the condenser, the refrigerant passes through an expansion device to an indoor heat exchanger, known as an evaporator. In the evaporator, moisture may be removed from the air, and the temperature of air blown over the evaporator coil is lowered. From the evaporator, the refrigerant returns to the compressor. Of course, basic refrigerant cycles are utilized in combination with many configuration variations and optional features. However, the above provides a brief understanding of the fundamental concept.
In more advanced refrigerant systems, a capacity of the air conditioning system can be controlled by the implementation of so-called tandem compressors. The tandem compressors are normally connected together via common suction and common discharge manifolds. From a single common evaporator, the refrigerant is returned through a suction manifold, and then distributed to each of the tandem compressors. From the individual compressors the refrigerant is delivered into a common discharge manifold and then into a common single condenser. The tandem compressors are also separately controlled and can be started and shut off independently of each other such that one or both compressors may be operated at a time. By controlling which compressor is running, control over the capacity of the combined system is achieved. Often, the two compressors are selected to have different sizes, such that even better capacity control is provided. Also, tandem compressors may have shutoff valves to isolate some of the compressors from the active refrigerant circuit, when they are shutdown. Moreover, if these compressors operate at different saturation suction temperatures, pressure equalization and oil equalization lines are frequently employed.
One advantage of the tandem compressor system is that better capacity control is provided, without the requirement of having each of the compressors operating on a dedicated circuit. This reduces the system cost.
Tandem compressors provide untapped potential for even greater control. The tandem compressors have not been provided in many beneficial combinations that would be valuable.
In some cases, while the system is operating in a cooling mode, the temperature level at which the air is delivered to provide comfort environment in a conditioned space may need to be higher than the temperature that would provide the ideal humidity level. Generally, the lower the temperature of the evaporator coil more moisture can be removed from the air stream. These opposite trends have presented challenges to refrigerant system designers. One way to address such challenges is to utilize various schematics incorporating reheat coils. In many cases, a reheat coil placed in the way of an indoor air stream behind the evaporator is employed for the purposes of reheating the air supplied to the conditioned space after it has been cooled in the evaporator, where the moisture has been removed as well.
While reheat coils have been incorporated into air conditioning systems, they have not been utilized in an air conditioning system having an ability to operate at multiple temperature levels.